Synergistic Assembly of a CoS@NiFe/Ni Foam Heterostructure Electrocatalyst for Efficient Water Oxidation Catalysis at Large Current Densities

Abstract Electrochemical water splitting is an ideal pollution‐free path to generate hydrogen at large scale, however, the development of highly catalytic electrocatalysts for the water oxidation reaction at large current densities is still a fundamental challenge. Herein, we report a novel, high‐wettability water‐oxidation electrocatalyst composed of an amorphous NiFe layer and CoS film on commercial nickel foam via a two‐step electrodeposition synthetic path. Benefiting from the strong interactions between the NiFe layer and CoS film, enlarged surface active sites and enhanced wettability, the CoS@NiFe/NF electrode exhibited an outstanding water oxidation performance at 10 mA/cm 2 with an overpotential of 175 mV in 1 M KOH solution and steadily delivered a current density of 1 A/cm 2 at merely 330 mV in 30 wt% KOH solution. Even at large densities, the CoS@NiFe/NF hybrids also showed excellent water oxidation stability and corrosion resistance for at least 24 h. Such a synergistic assembling approach to fabricate a CoS@NiFe/NF heterostructure together with excellent OER performance may be a promising strategy for rationally building and designing heterostructural electrocatalysts towards highly efficient water oxidation reaction.